The Jacoby Minor optional convention

At least 6 Clubs and less than 5 HCP. Opener
rebids 4 ♣ and responder passes

At least 6 Clubs, a singleton or
void and at least 5 HCP. Opener rebids 4 ♣. Responder shows
where the shortage lies by bidding as follows:

4 ♥
with a shortage in
Spades

4 ♠ with a shortage in Hearts

4NT is Blackwood

If responder believes a slam is possible he shows
any first or second-round control

4 ♣

At least 6 Diamonds and less than 5 HCP. Opener
rebids 4 ♦ and responder
passes

At least 6 Diamonds, a singleton or
void and at least 5 HCP. Opener
rebids 4 ♦. Responder
shows where the shortage lies, or shows controls, as for the major suit
responses to the 3
♠ bid above. Alternatively, with an interest in slam, responder can bid
4NT which is Blackwood

Note that the Jacoby Minor over 2NT, and Gerber, are
mutually exclusive